Abstract: Objective: To study the immunomodulatory effects of yeast β-glucan and zinc compound formula on cyclophosphamide (CTX)-induced immunosuppression in immature mice. Methods: 48 BALB/c mice with 3-week old were randomly divided into three groups: The control group, the model group, and the compound-treated group. The mice in the compound-treated group were treated with yeast β-glucan and zinc complex (corresponding to yeast β-glucan: 90 mg/kg/d, zinc: 2.8 mg/kg/d), while the mice in the control group and model group were fed distilled water in the same volume. On the 14 and 15 d, model group and compound-treated group were injected with CTX to establish immunosuppressive model. After 28 day’s administration, each group was divided into two subgroups. Subgroup I was used to detect immune organ index, numbers and activities of immunocytes and cytokines. Subgroup II was used to conduct serum haemolysin test and hemolytic plaque test. Result: Compared to the model group, yeast β-glucan and zinc compound formula could significantly (P<0.05) improve mice immune organs indexes, promote the proliferation of spleen lymphocytes and increase the number of intestinal goblet cell, also could highly significantly (P<0.01) improve the serum half hemolysis value (HC₅₀), increase the number of hemolytic plaques, enhance NK cell activity, raise the concentration of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) in peripheral blood, the numbers of white blood cell (WBC), Peyer's patches. Conclusion: The yeast β-glucan and zinc compound formula had the function of enhancing humoral immunity, NK cell activity and intestinal mucosa immunity in immature mice.